It is "99 percent certain" Ahmed Mohamed Nasser al-Soofi and Hezam al-Murisi will be freed without charge, national prosecutor's office spokesman Ernst Koelman told The Associated Press in a phone interview.
"There is a big chance it will be soon," he added. He gave no more details, saying he was still awaiting official confirmation from prosecutors.
The men were arrested Monday in Amsterdam on a United Airlines flight from Chicago following a request from U.S. law enforcement officials. Under Dutch law, they can be held for up to three days and 15 hours before they must be brought before an investigating judge or released.
Al-Soofi's Dutch lawyer Wouter Hendrickx said he had not yet had word from prosecutors that his client would be released. He told the AP earlier that al-Soofi insists he is innocent.
"He says 'I have no connections to terrorist activities whatsoever,"' Hendrickx said.
Hendrickx said al-Soofi was on his way to Yemen to visit his family when he was detained.
Al-Soofi and al-Murisi missed flights to Washington Dulles International Airport from Chicago, and United Airlines then booked them on the same flight to Amsterdam, a U.S. government official said. The men were sitting near each other on the flight, but not together.
Al-Soofi also raised suspicions in the United States on Sunday because he was carrying $7,000 in cash. An inspection of his checked luggage uncovered a cell phone taped to a small bottle, multiple cell phones and watches taped together, and a knife and box cutter, according to a U.S. official who had been briefed on the investigation.
None of the checked items violated U.S. security rules, so authorities allowed al-Soofi to fly. But his bags later were transferred to another flight and were not on the flight to Amsterdam, Dutch prosecutors said.
Al-Soofi and al-Murisi changed their travel plans at the last minute and took a direct flight to Amsterdam, raising suspicion among U.S. officials.
However, a U.S. law enforcement official said Tuesday that following FBI inquiries neither man is likely to be charged in the U.S.
Hendrickx said he has not yet received a case file from prosecutors so he could not discuss further details of the case.
He said the two men were being held in separate cells at a jail in the central Dutch town of Houten.